PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Polarisation and anisotropic media · Polarisation and anisotropic media
What an Instrument Can See, Ch Anisotropic media: the dielectric tensor and the index ellipsoid
Problem
Muscovite mica is biaxial, with principal refractive indices at 589 nm nx=1.560, ny=1.594, nz=1.598 (labelled so that nx<ny<nz).
((a)) Using the central-section construction (a direction is an optic axis when the central section of the index ellipsoid perpendicular to it is a circle), derive the angle θ that each optic axis makes with the z-axis, given that both axes lie in the xz-plane.
((b)) State the angle each optic axis makes with the x-axis instead, and the angle between the two optic axes.
((c)) Mica cleaves into sheets whose faces are perpendicular to x. Find the thickness of a zero-order quarter-wave plate for 589 nm light at normal incidence on such a sheet, and say what the small gap nz−ny that puts the optic axes near x means for mica as a wave-plate material.